The present invention relates to a substrate transferring apparatus for transferring a large-sized substrate such as an LCD substrate, and to a substrate processing apparatus using the substrate transferring apparatus.
In the manufacture of liquid crystal displays (LCD), a circuit pattern is formed by the so-called lithography technique. That is, the LCD substrate, made of glass, is coated with photo resist liquid to form a resist film, the resist film is exposed to a pattern correspond to the circuit pattern, and the LCD substrate is developed to form the circuit pattern thereon.
Conventionally, a series of coating/developing processes is carried out by a system in which the respective processing apparatus are incorporated. Such a system comprises processing units for performing the respective processes such as a cleaning process, a coating process, a developing process and a heating process, and a cassette station on which a cassette for containing a plurality of substrates is mountable. A substrate transferring apparatus is provided between the cassette station and a transferring mechanism of each processing unit to receive and transfer the substrate.
Such a substrate transferring apparatus is structured to be movable on a carrying path formed along the plurality of cassettes arranged in parallel in the cassette station. The substrate transferring apparatus comprises a support member, which is called tweezers, for supporting the substrate, a base member for supporting the support member to be movable back and forth, a lifting member, provided to be movable upward and downward, for supporting the base member to be rotatable in a horizontal plane, and a hold-and-guide member, formed on both sides of the lifting member, for supporting and guiding the lifting member when the lifting member moves up and down. The hold-and-guide member is structured such that its upper end is always positioned at a lower portion of the base member not to prevent the rotation of the base member.
By the way, the need for enlarging the size of the LCD substrate has recently been increased more and more. Specifically, there has been needed the size of the substrate, which is greatly enlarged, for example, 830.times.650 mm from the conventional size of 650.times.550 mm. If the size of the substrate is greatly increased, an amount of deflection of the substrate is increased in the cassette. Therefore, the distance between substrates in the cassette must be increased. From the viewpoint of improvement of throughput, the number of substrates to be contained in one cassette must be maintained. Therefore, the height of the cassette is increased, the motion strokes of the lifting member of the substrate transfer mechanism is increased. In this case, the upper end of the hold-and-guide member is positioned at the lower portion of the base member. For this reason, the upper end position is adjusted to a position where the rotation of the base member is prevented in receiving/transferring the substrate from/to the lower stage of the cassette. As a result, there emerges a need for reducing the lower end position of the guide and support member to be lower than a floor surface. This forces a user to do additional work, unfavorably. Also, if the hold-and-guide member is structured to be projectable upward than the base member in order that the base member is rotatable, the transferring apparatus itself will be extremely enlarged.